Premium
Chemie von a‐Aminonitrilen . Aldomerisierung von Glycolaldehyd‐phosphat zu racemischen Hexose‐2,4,6‐triphosphaten und (in Gegenwart von Formaldehyd) racemischen Pentose‐2,4‐diphosphaten: rac ‐Allose‐2,4,6‐triphosphat und rac ‐Ribose‐2,4‐diphosphat sind die Reaktionshauptprodukte
Author(s) -
Müller Daniel,
Pitsch Stefan,
Kittaka Atsushi,
Wagner Ernst,
Wintner Claude E.,
Eschenmoser Albert,
Ohlofjgewidmet Güntner
Publication year - 1990
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19900730526
Subject(s) - chemistry , pentose , glycolaldehyde , hexose , ribose , yield (engineering) , formaldehyde , sugar phosphates , pentose phosphate pathway , diastereomer , medicinal chemistry , organic chemistry , stereochemistry , nuclear chemistry , phosphate , catalysis , enzyme , fermentation , materials science , glycolysis , metallurgy
Chemistry of α‐Aminonitriles. Aldomerisation of Glycolaldehyde Phosphate to rac ‐Hexose 2,4,6‐Triphosphates and (in Presence of Formaldehyde) rac ‐Pentose 2,4‐Diphosphates: rac ‐Allose 2,4,6‐Triphosphate and rac ‐Ribose 2,4‐Diphosphate Are the Main Reaction Products Glyclaldehyde phosphate aldomerizes in aqueous NaOH solution to a product mixture containing the racemates of the two diastereoisomeric tetrose 2,4‐diphosphates and eight hexose 2,4,6‐triphosphates. At room temperature in the absence of air and after 7 days, a solution 0.08 M in glycolaldehyde phosphate (=formylmethyl dihydrogenphosphate)and 2 M in NaOH gives products, in up to 80% yield, with a tetrose/hexose derivative ratio of ca 1:10 and with rac ‐allose, 2,4,6‐triphosphate comprising up to 50% of the mixture of sugar phosphates. When the reaction is run under the same conditions but in the presence of 0.5 mol‐equiv. of formaldehyde, sugar phosphates are formed in up to 45% yield, with pentose 2,4‐diphosphates now predominating over hexose triphosphates by a ration f 3:1 rac ‐Ribose 2,4‐diphosphate is found to be the major component, the ratios am ribose, arabinose, lyxose, and xylose 2,4‐diphosphates being 52:14:23:11 in a representative experiment. The pentose diphosphates are constitutionally stable under the reaction conditions (observed for 23 weeks), but the diastereoisomeric ratios slowly change with time (tc 22:34:30:14 after 23 weeks), showing that ribose 2,4‐diphosphate is not the thermodynamically favored diastereoisomer. The observed product distributions in both the pentose and the hexose series (after 1 week) reveal an aldolization mode that is preferentially erythro in the product‐determining step (the reaction of glycolaldehyde phosphate as its enolate with glycerinaldehyde 2‐phosphate and tetrose 2,4‐diphosphate, respectively). An attempt is made to rationalize both this fact and the kinetic predominance of ribose 2,4‐diphosphate in the pentose series and allose 2,4,6‐triphosphate in the hexose series. Their configuration along the C‐chain can be interpreted as corresponding to a minimum number of 1‐5 repulsions in the packing of phosphate and OH substituents and minimal steric interaction between substituents at the reaction centers in the transition state of the product‐determining step. The aldomerization of glycolaldehyde phosphate in the presence of formaldehyde is a variant of the formose reaction, It avoids the formation of complex formose product mixtures, largely as a consequence of the fact that aldoses which are phosphorylated at the C(2)